The "brake ducts" are festooned with winglets that do not directly aid the cooling of the brakes. Yet they remain. So why not winglets on a mirror, which do not directly aid the redirecting of photons.

Because they are in the legality box of the brakes. The winglet however abuses a clarification the FIA made allowing mirrors on the halo.

In a pinch Ferrari mightcould argue that the fins are an aero stabilizer for the mirror, an air-anchor, an aero-stay, if you will.

Definitely not, First of all, they haven't ran such a thing before. This alone would imply that they are very much capable of making structurally sound mirror mounts, making such a thing unnecessary.

Second of all, aerodynamic load changes with speed, which would thus mean it's rigidity increases with speed.

1. You don't know how many laps each tire had done
2. The Mercs were doing repeated burnouts during pre-season testing to further highlight the damage, this was widely reported and tweeted about and commented on by Vettle

1. You don't know how many laps each tire had done
2. The Mercs were doing repeated burnouts during pre-season testing to further highlight the damage, this was widely reported and tweeted about and commented on by Vettle

Very true, if I remember correctly, Mercedes was entering the pitlane and 'revving' the engine without making a pit stop.

Why would Ferrari commit the whole race weekend, and run them all through two days of testing, when they will never see the light of day again?

The same reason (apart from the fact that according to the regulations they were technically legal) that they were allowed at the GP. The modifications would be too extreme as it is not a quick overnight simple swap fix - as new halo fairing is required. Guess the car goes back to Maranello to be modified and repaired before being sent to Monaco? Mirrors will be updated, modified or removed then.

Probably because they'll just mount the mirrors from the upper arm without the stalk and then the FIA can't complain and they still do the same job

Sadly all halo mounted mirror stalks must now join the mirror on either its in-board surface or the bottom surface, and multiple stalks aren't permitted unless the structural requirement of said stalks are demonstrated.

Sadly all halo mounted mirror stalks must now join the mirror on either its in-board surface or the bottom surface, and multiple stalks aren't permitted unless the structural requirement of said stalks are demonstrated.